When a golf club is swung, the head attached to the end of the club reaches a velocity of 40 to 50 m/s in the case of long clubs such as a driver. It is known that when a physical body travels through the air at such a high speed, airflow turbulence arises around the body. In this case, depending on the shape of the body, the turbulence of the air streams that flow around the body is complex and exerts a major influence on the motion of the body.
The head of a golf club, particularly on a wood club, has a three-dimensionally complex shape. Because the club head travels at a high speed as noted above, the shape is thought to exert a major influence on the aerodynamic properties and also to affect, for example, the “swing through” feel during the swing and the stability of the club head trajectory. For this reason, understanding the causal relationship between the club head shape and the aerodynamic properties contributes significantly to club development.
Generally, when investigating the changes in aerodynamic properties that arise from changes in the shape of a physical body such as a club head, numerous physical prototypes of differing shapes are actually fabricated and evaluations of the aerodynamic properties are carried out by performing wind tunnel tests to investigate changes in air flow or by investigating changes in club head trajectory and speed when the club is swung with a swing robot.
However, such experimental evaluation based on actual physical prototypes is time-consuming and costly, in addition to which it is difficult to arrive at a clear understanding of the aerodynamic properties from the resulting changes in air flow. Moreover, establishing a clear causal relationship between the aerodynamic properties and the club head performance is not always easy. Hence, club heads which have been newly designed based on evaluation results obtained by experimentation often fail to achieve the intended performance. In such cases, it is necessary each time to design and test-produce a new club head and determine its aerodynamic properties, resulting in further outlays of time and expense, and thus making efficient club development impossible.
No prior-art publications relevant to the present invention which concern club heads as in this application have been found, although prior art relating to the aerodynamic properties of golf balls include JP-A 2006-275722, JP 03626113, JP 03532528 and JP 03477694.